Sergei Nikolayevich Bulgakov was a Russian Orthodox theologian, priest, philosopher, and economist. Orthodox writer and scholar David Bentley Hart has said that Bulgakov was "the greatest systematic theologian of the twentieth century." Father Sergei Bulgakov also served as a spiritual father and confessor to Mother Maria Skobtsova.

David Bentley Hart is an American writer, philosopher, religious studies scholar, critic, and theologian. Reviewers have commented on Hart's baroque prose and provocative rhetoric in over one thousand essays, reviews, and papers as well as nineteen books. From a predominantly Anglican family background, Hart became Eastern Orthodox when he was twenty-one. His academic works focus on Christian metaphysics, philosophy of mind, Indian and East Asian religion, Asian languages, classics, and literature as well as a New Testament translation. Books with wider audiences include The Doors of the Sea, Atheist Delusions, That All Shall Be Saved, and Roland in Moonlight.